Bulbs, Rhizomes, Corms and Tubers

Iris Spring blooming bulbs are a welcomed sight after a long winter. Bulbs are available in a wide variety of sizes, colors, and forms and can provide a great deal of color and textural interest in small or large areas. They require minimal effort on the part of the gardener and landscape professional, and they add a great deal of beauty to the landscape.

There are several types of bulbs and bulb-like structures: true bulbs, which are divided into two groups - scaly bulbs like Asiatic lilies (Lilium asiatic) and tunicate bulbs like tulips (Tulipa species); tubers like dahlias (Dahlia hybrids) have leathery skin and feature "eyes" that are buds; rhizomes such as iris (Iris hybrids) are really underground stems and grow just below or on the soil surface. Crocus (Crocus vernus) and gladiolus (Gladiolus hybrids) are examples of corms, a compressed stem that contains food and has a bud on top. Bulbs and bulb-like structures share something very important in common: they serve as storage structure for food that provides the energy for the plant to grow, bloom and complete its lifecycle each year. The foliage is responsible for photosynthesis, creating energy for the plant and storing it in the bulb.

Bulbs may be hardy (spring- and early summer-flowering) or tender (summer-flowering). Hardy bulbs are planted in the fall, generally before the first frost, and can survive (and indeed require for sprouting) the cold winter months. Most hardy bulbs, such as tulips and daffodils, can be left in the ground to flower year after year. Examples of hardy bulbs are tulips, daffodils (Narcissus species and hybrids), iris, crocus, and lilies. Here are some recommended websites for information about hardy bulbs:

Tender bulbs including dahlias, begonias (Begonia tuberosa) and gladiolus are planted in the spring for summer bloom. They cannot survive cold winter temperatures and must be dug each fall and stored for the winter indoors in a cool, dry place. Tender bulbs are planted in the spring after the soil has warmed. For facts about how to care for and store tender bulbs, visit Storing Tender Bulbs and Bulb-like Structures and Bulbs - Digging and Storing Non-Hardy Bulbs from the University of Minnesota Extension Service. Another site is Cannas, Dahlias, Gladiolus & Tuberous Begonias: Digging, Storing.

For more on proper plant selection based on site and plant characteristics, see Plant Elements of Design plant selection database.

For information about specific tender bulbs, visit these sites:

There are many websites, books and publications about bulbs. If you are looking for an all-inclusive website about bulbs, visit the Netherlands Bulb Information Centre website. It is written in English, and provides everything you need to know about selecting bulbs, caring for them, seasonal blooming, purchasing, etc. Visit the International Bulb Society website for communication with other bulb enthusiasts and access to articles and member newsletters (You must be a member to access various areas of the site). Another good website for general information about bulbs, corms, rhizomes, and tubers, is the Ohio State University Extension Master Gardener online publication, Herbaceous Ornamentals: Perennials, Annuals, and Bulbs

Click on any of the following headings and link to chapters that explain care and maintenance of herbaceous plants.

Propagation
Dividing Plants
Dividing Rhizomes
Starting Plants from Seed
Collecting and Saving Seed
Self-Sowing Plants
Transplanting Seedlings, Cuttings and Divided Plants
References

Staking, Supporting and Training Plants
Methods of Supporting Plants
Materials & Structures
Training to Improve Plant Health (FUTURE)
Training Plants for Ornamental Purposes (FUTURE)
References

Pruning
Cutting Back Plants
Pruning for Plant Form
Pruning to Prevent Disease (FUTURE)
Deadheading and Pinching Back (FUTURE)

Mulching & Watering
Why Use Mulch?
Application of Mulch
Mulching for Weed Control
Mulching for Winter Protection
Mulching for Moisture Control
Organic Mulches
Synthetic Mulches
Watering Your Landscape
How to Determine the Frequency and Rate of Watering
Water Quality and its Effect on Plants
References

Nutrition, Fertilizers, and Compost
The Basics of Plant Nutrition and Fertilizers
Soils (FUTURE)
Compost (FUTURE)
Fertilizer: the Do's and Don'ts
Organic Fertilizers (FUTURE)
Inorganic Fertilizers (FUTURE)
Salt Tolerant Plants

Weed Management
Weed Identification and Lifecycles
Cultural Management Methods for Weed Control
Pruning for Weed Control (FUTURE)
Herbicides
Understanding Labels (FUTURE)
Alternatives to Chemical Herbicides (FUTURE)
References

Diseases and Insects
Diseases
Insects
Integrated Pest Management (FUTURE)
References

References:

American Daffodil Society, http://www.daffodilusa.org

American Hemerocallis Society, http://www.daylilies.org/daylilies.html

American Iris Society, http://www.irises.org

International Bulb Society, http://www.bulbsociety.com

Meyer, Mary H., list of bulbs, 2000 core course packet, HORT 1011, University of Minnesota.

Netherlands Bulb Information Center, http://www.bulb.com

Ohio State University Extension "Herbaceous Ornamentals: Perennials, Annuals and Bulbs", Master Gardener manual, Jack Kerrigan and Margaret Nagel. http://hcs.osu.edu/mg/manual/herbac3.htm

University of Minnesota Libraries, Bell Museum, "Tulips", Barbara Schulman. 2002 http://www.bell.lib.umn.edu/Products/tulips.html

University of Minnesota Extension, "Spring Bulb Basics", Yard & Garden News, April 1, 2000, vol. 2, no. 4, Deborah L. Brown. http://www.extension.umn.edu/yardandgarden/YGLNews/YGLN-Apr0100.html#bulbs

University of Minnesota Extension, "Storing Tender Bulbs and Bulb-like Structures", FS-1117-GO, Mary H. Meyer, 1998. http://www.extension.umn.edu/distribution/horticulture/DG1117.html

University of Minnesota Extension, "Growing Dahlias", FS-1115-GO, Paul E. Read and Deborah L. Brown, 1993. http://www.extension.umn.edu/distribution/horticulture/DG1115.html

University of Minnesota Extension, "Growing Daylilies", FS-1106-GO, Mary H. Meyer, 1999. http://www.extension.umn.edu/distribution/horticulture/DG1106.html

University of Minnesota Extension, "Iris for Northern Gardens", FS-1113-GO, Deborah L. Brown, 1998. http://www.extension.umn.edu/distribution/horticulture/DG1113.html

University of Minnesota Extension, "Selecting Lilies for Your Garden, FS-1112-GO, Anne M. Hanchek and Jane E. Bolla, 1997. http://www.extension.umn.edu/distribution/horticulture/DG1112.html

University of Minnesota Extension, "Amaryllis Care", INFO-U publication #438, Deborah L. Brown and David Whiting, revised 1997. http://www.extension.umn.edu/info-u/plants/BG438.html

University of Minnesota Extension, "Bulbs - Digging and Storing Non-Hardy Bulbs", INFO-U publication #453, Jean Hjellming and Patrick Weicherding, revised 2000. http://www.extension.umn.edu/info-u/plants/BG453.html

University of Minnesota Extension, "Bulbs - Tulips and Daffodil Care After Bloom", INFO-U publication #455, Anne Hanchek and Deborah L. Brown, revised 1998. http://www.extension.umn.edu/info-u/plants/BG455.html

University of Minnesota Extension, "Saving Forced Bulbs", INFO-U publication #425, Deborah L. Brown and David Whiting, revised 1999. http://www.extension.umn.edu/info-u/plants/BG425.html

University of Minnesota Extension, "Spring Bulbs and Hard Frosts", INFO-U publication #458, Doug Foulk and Deborah L. Brown, revised 1999. http://www.extension.umn.edu/info-u/plants/BG458.html

University of Nebraska, "Growing Gladiolus", G87-852-A, Amy J. Greving. Revised March 1992. http://www.ianr.unl.edu/pubs/horticulture/g852.htm

University of Rhode Island, "Forcing Bulbs", Greenshare, Sharon Bale, University of Kentucky. http://www.uri.edu/ce/factsheets/sheets/forcebulbs.html

University of Rhode Island, "Iris Culture", Greenshare, Leslie Diebec, Ohio State University Extension. 2000. http://www.uri.edu/ce/factsheets/sheets/iris.html

University of Wisconsin Cooperative Extension, "Cannas, Dahlias, Gladiolus & Tuberous Begonias: Digging, Storing", Info Source, #453, Sharon L. Morrisey, 1996. http://cf.uwex.edu/ics/infosource/fullrecord.cfm?IDnumber=540

University of Wisconsin Extension, "Iris: Dividing Iris", Info Source, #449, Sharon L. Morrisey, 1996. http://cf.uwex.edu/ics/infosource/fullrecord.cfm?IDnumber=545

University of Wisconsin Extension, "Bulbs: Care of Tulips / Daffodils after Blooms", Info Source, #455, Sharon L. Morrisey, 1996. http://cf.uwex.edu/ics/infosource/fullrecord.cfm?IDnumber=538